diff --git a/src/primaite/simulator/system/services/ntp/ntp_client.py b/src/primaite/simulator/system/services/ntp/ntp_client.py
index e8c3d0cb..ccb2cbe7 100644
--- a/src/primaite/simulator/system/services/ntp/ntp_client.py
+++ b/src/primaite/simulator/system/services/ntp/ntp_client.py
@@ -127,6 +127,7 @@ class NTPClient(Service):
         super().apply_timestep(timestep)
         if self.operating_state == ServiceOperatingState.RUNNING:
             # request time from server
-            self.request_time()
+            if self.ntp_server is not None:
+                self.request_time()
         else:
             self.sys_log.debug(f"{self.name} ntp client not running")